1. Field of the Invention
The present invention concerns a force-measuring apparatus, particularly a weighing cell, with a load receiver for receiving the force that is to be measured and a force-transmitting device for transmitting at least a partial amount of the force to be measured from the load receiver to a measuring transducer that delivers a signal corresponding to the force to be measured. The load receiver is guided in planar translatory motion in relation to a stationary part of the force-measuring apparatus by two parallelogram guides (guide links) that extend in two mutually parallel planes, are rigid with regard to deformation within their respective planes and have elastic flexibility in the transverse direction of the planes. Each of the two parallelogram guides is connected at one end (with respect to its lengthwise direction) to the load receiver and at the opposite end to the stationary part of the force-measuring apparatus. A parallelogram plane is defined by the lengthwise direction of the guides and the path of motion traveled by the load receiver. The force-transmitting device has at least one force-transmitting lever that receives its input force through a coupling from the load receiver and is rotatable in relation to a fulcrum axis that is fixed on a support portion of the stationary part extending between the two parallelogram guides in a plane that is parallel to the common plane of the parallelogram guides.
2. Description of the Related Art
It is a known design concept for weighing cells of this kind to be assembled from numerous individual components that need to be either rigidly attached to or movably pivoted at the stationary part. In particular, the pivot points of the parallelogram guides and the lever are located on the stationary part. Positional changes of these pivot points that are caused by the force to be measured will impair the measuring accuracy. Therefore, the stationary part needs to have a particularly high degree of structural rigidity.
It is also a known concept (DE 41 19 734 A1) to configure the stationary part, the parallelogram guides, the load receiver and the lever as a continuum of interconnected material portions of a monolithic material block, whereby in particular the assembly process of the corresponding separate components is eliminated. However, the separation of the individual material portions from the material block, e.g., by the method of spark erosion, represents a relatively exacting procedure, particularly in the case where the apparatus will have to meet a high level of measuring accuracy and, therefore, the thinned-down material domains by which the material portions are movably connected have to be formed with a commensurate degree of precision.